JP2008-37133A published by the Japan Patent Office in the year 2008 proposes a beat noise preventing device that prevents beat noise in an electric vehicle that includes drive wheels each driven with an in-wheel motor equipped with an electric motor and a reduction gear.
Beat noise occurs as operating noises originating from a plurality of in-wheel motors become superposed. Such beat noise is suppressed in the prior art by adjusting the frequency of the operating noise at the electric motor or the reduction gear in each wheel.